Quote:Google customers who use the SMS functionality of Google Calendar will have it replaced with notifications or emails in January 2019.

Google published information about the change on the official G suites Update blog on the Googleblog website.

Quote:Starting on January 7, 2019, SMS notifications from Google Calendar will no longer be available.

Google provides no explanation for the change, only that Calendar supports in-app notifications and that users who like to receive notifications from the app can use that functionality instead.

Google customers who have set up SMS notifications on Google Calendar will have those changed to notifications or emails. Customers who have Calendar open in a web browser or use the Google Calendar application for Google's Android operating system or Apple's iOS operating system will get event notifications by the browser or app on the device instead.

Quote:Since Calendar offers in-app notifications, you can still get notified, regardless of your device or connection.

Customers who set up SMS notifications for "new events, changed events, canceled events, or event responses" will receive emails with notifications about those events instead.

Full reading: https://www.ghacks.net/2018/11/19/google-removes-sms-notifications-from-google-calendar/